Subterranean deposits of coal, shale and other formations often contain substantial quantities of methane gas. Vertical wells and vertical well patterns have been used to access coal and shale formations to produce the methane gas. More recently, horizontal patterns and interconnected wellbores have also been used to produce methane gas from coal and shale formations and/or to sequester carbon dioxide. Limited production and use of methane gas from such formations has occurred for many years because substantial obstacles have frustrated extensive development and use of methane gas deposits in coal seams.
One such obstacle is the potential for collapse of the wellbore(s) during the production of the methane gas. A solution to this problem is to run casing/liners in the producing zone. A casing with properly sized openings prevents the collapsed coal from plugging the hole, which would prevent optimum production. The use of multiple wellbores from the same parent well also improve production, but this creates a new set of obstacles. A junction must be made between the main wellbore and the respective lateral wellbores. If solids production (coal) is anticipated this junction should allow access to both the lateral and the main wellbore below the lateral for clean out purposes, which can create obstacles in the completion